1. Field of the Invention
This invention relates to a control for a drive unit and particularly for the drive unit of a power vehicle, in particular, a scoop loader, with a primary power source, preferably a piston internal-combustion engine, in particular, a diesel engine.
2. Description of the Prior Art
The invention more particularly relates to a drive aggregate of a power vehicle such as a scoop loader with a primary power source having an adjusting device that is connected with a piston loaded with a control pressure in an operating cylinder and capable of sliding against the force of a spring and a hydrostatic transmission that is adjustable in both directions of output rotation and whose regulating unit is connected with a servo piston that is capable of sliding in an operating cylinder whose pressure loading is regulated by a control valve having a valve member connected with a receiver piston slidable in a receiver cylinder having two pressure chambers, one of which is capable of being loaded with an arbitrary control pressure and when the control pressure assigned to the primary power source is dependent upon the control pressure assigned to the hydrostatic transmission. Such a control that has proven well in practice is already known (DE-OS No. 30 35 152). Although it has proved out very well, there is one disadvantage in that in switching from one direction of output rotation to the other the exchange of control pressure from one side of the receiver cylinder to the other can occur more rapidly than the actual change in direction of output rotation due to the inertia of reversal of the regulating unit of the hydrostatic transmission. That is, a control pressure that is already considerably increased and is assigned to a certain direction of output rotation can be present, while the output shaft is actually still turning in the other direction. If the adjustment of the regulating unit of the primary power source is dependent only on the control pressure that acts on the transmission or is even dependent only on the adjustment of the actuation element with which the control pressure is actuated, the primary power source can thus be set at an increased power output while the transmission output shaft is actually still turning in the opposite direction.